- Try to avoid building Python or extension modules with problematic
llvm-gcc compiler.
- Since Xcode 4 removes ppc support, extension module builds now
check for ppc compiler support and automatically remove ppc and
ppc64 archs when not available.
- Since Xcode 4 no longer install SDKs in default locations,
extension module builds now revert to using installed headers
and libs if the SDK used to build the interpreter is not
available.
- Update ./configure to use better defaults for universal builds;
in particular, --enable-universalsdk=yes uses the Xcode default
SDK and --with-universal-archs now defaults to "intel" if ppc
not available.